Means for uniting sheet metal



P 1942- o. KLEINSCHMIT MEANS FOR UNITING SHEET METAL Filed March 17, 1938 6 Sheets-Sheet 1 OSKAR KZLEINSQHMIT BY M.&MM7YUMJ INVENTOR A T T Y8,

'Sept. 29, 1942. o. KLEINSQHMIT 2 I MEANS FOR UNITINQ SHEET METAL Filed March 17, 1938 6 Sheets-Sheet 2 INVENTOR O-SKAR KLEINSQHMIT p 9, 9 O. KLEINSCHMIT MEANS FOR UNITING-SHEET METAL 6 Sheets-Sheet 3 Filed March 17, 1938 mvNToR QSKAR KLEINSCHM 1 84 &7 f.

/ TTys.

Sept. 29, 1942. E o. KLEINSCHMIT MEANS FOR UNITING SHEET METAL 6 Sheets-Sheet 5 Filed March 17, 1938 -12 E OSKAR KLEINSCHMIT BY ATTYS Sept. 29, 1942- o. KLEINSCHMIT 2,297,223

mums FOR UNITING SHEET METAL Fild March 1'7, 19:58 6 Sheets-Sheet 6 possible limits.

' I to employed for other; purposes.

' In comparison with the riveting machine which Patented Sept. 29, .1942.

UNITED {STATES PATENT OFFlCE ron nifzi ijfi snsn'r-rmrar. V

Oskar Kleinschmit, Leipzig-Plagwitz, German'yt vested in the Alien Property Custodian Application March 17, 1938, Serial No. 196,498 I In Germany'March- 18, 1937 4 Claims. The improvement in the manufacture of sheet steel in the metal industry has recently reached tor cars, another branch of industry which has been aflected thereby is the construction of allhas hitherto exclusively beenflused it is possible i by employing the machine of the present invention to obtain not only many times the output but also a reduction of the cost to a fraction or the former amount. At the same time the stitched points exhibit greater strength than riveted points as regards continuous loading of the finished work. There is also the advantage that metal aircraft. The wall surfaces ofmetal car bodies and all-metal aircraft consist of overlap! ping metal sheets of considerable mechanical strength which have to be united in a permanent and reliable manner. Also the points at which they are united must be very. closev together so that the vibrations, which occur at high speed flight for example, are kept within the smallest Hitherto, such metal sheets have been united the new method of stitching can be used more readily than the more expensive riveting machine at points which are dimcult of access.

By bending the shanks of the cramps outwardly greater strength is obtained than by '.bending the shanks inwardly, presumably beby means of rivets which are, introduced into pre-formed holes and then up-set at both ends.

'A special automatic riveting machine has been developed which" has a relatively high capacity but which has the drawbacks that it requires preformed holes 3-5 mm. in size to take the rivets -'which are then upset at both ends; moreover,

the purposes for which wire stitching machines have hitherto been employed the thicknesses of material to be stitched in accordance with the present invention are only small but very .much

stronger material is involved This maximum driving force isobtained in that onthe one hand 'the camshave ,an appreciably smaller throw corresponding to the smaller stroke so that with a constant power inputagreaterpositive working pressure can be obtained, andon the other hand the time available for driving'the cramps at the points where large generation of force is necessary'can'be made large at thecost of the time available. for those movements which serve solely for the cramps'fland which are small in comparison with the corresponding movements in the wire stitching machines hithercause the bending outwardly causes the holes 7 which are formed by the penetration of the cramp'to be'filled better than if there is the double bending inthe same direction as when bending inwardly. The bending outwardly has in addition the very material advantagev that the back of the cramp when being driven .can be forced into the upper sheet metal layer so' that the stitching point does not consist of two thick-' nesses of sheet metal plus two thicknesses of wire, but of two thicknesses of sheet metalplus than 10 mm. long, as tests have shown thatthe load can then be increased appreciably.

Experiments have also shown that wire con siderably thicker than that customary for stitching purposes in wire-stitching machines in the book-binding industrycan be employed. In this waythe utility of the invention is' further augmented and far exceeds that of the riveting ma chines hitherto exclusively employed for the same purpose. The shape of the wire employed.

is unimportant. It may be round, rectangular or square, and in spite of the highest-strength of the work it is not necessary to employ wire of the same strength. Experiments have shown that iron wire penetrates harder material cleanly if it'is driven. with the requisiteforce, and

a during the driving period the cramp is entirely enclosed in its guides-so that it; cannot distort. When securing metal plates together by the method and machine according to theprwent invention,-the cramp-which may conveniently be The material which produced from a length of wire which is fed to the machine-itself constitutes a punch which from the precisely vertical direction when bein forced through the work. However, with the arrangement as set out above in which the shanks are completely enclosed in guides above the work during the driving operation, this deflection does not occur to any appreciable extent. This makes earn 8 effects the upward and downward movement of a member I which slides in thehousing and which at the bottom carries interchangeable right and left-hand bending members ll (Figs. 7-11) wherebythe length of wire which forms the cramp and which is introduced horizontally as a straight piece of wire is bent into n-form over a block l2. On the inside these bendin members II have grooves I3 in which are guided the shanks of the cramp, the grooves being com- 'pletely closed-by means of the cramp support it possible, according to another feature of the invention, to support the work on a matrix number, which forms a closely fitting guide on three sides for the projecting portion of each shank of the cramp which is driven through and pro jects from the work. The matrix member is provided with a slot for each shank, the slots being substantially of the same width as the shanks and of such a length as is necessary for the length of the shank of the cramp which has to be accommodated therein when it projects beneath the work before being bent over against the work. The slots terminate at a sharp edge in the surface of the matrix member so that the work is supported as close as possible to the points where the punch-like shanks of the cramps are driven through. The surfaces engaging the work "from above and below are preferably concave and convex respectively, advantageously in the form of a spherical cap. These surfaces then tend to cause the work to become convex upwardly at the point where the cramp is driven, whereas the cramp driving operation tends to bend it in the opposite direction so that as a result a substantially straight surface is maintained. One embodiment of a machine according to the invention is shown by way of example in Figs. 1 to 13 of the accompanying drawings in which:

Figure 1 is a front view of the machine, Figures 2 and 3 show a section along the line 11-11 in the two extremepositions of the stitching mechanism,

Figure 4 is asection along the line IVIV of Figure 1,

Figures 5 and 6 are sections along the lines V--V and VIVI respectively of Figure 1,

Figures 7-11 show details, Figure 12 is a side view of the entire machine and Figure 13 shows the mechanism for adjusting for different thicknesses of work to be stitched.

The framework l (Figs. 2 and 12) carries at 2 the mechanismfor forming and driving the on the shaft 3 in the housing 2 is a crank 6, cam

discs 8 and 9 and also a cam H) on the cam disc 8 for moving the cramp forming parts. The

28 which slides between the limbs of the cramp. The driver I4 which drives the r1-shaped cramp in front of it is also guided in the grooves l3 above the shanks of the cramp. This cramp supv port 28 is gradually expelled from beneath the cramp against spring action during the cramp driving operation but maintains the cram channel constantly closed during that operation. Also guided in the member 1 is the driving plunger l5 (Figs. 7-11) which carries the driver It. The crank strap 6' is secured to the plunger l5 which is guided in the housing 2 and 'when the cramp has been bent into r1 -shape it is carried downwardly by the driver II at the appropriate moment and driven through the work W (Figs.'2 and 3). The cam 9 serves for advancing a new length of wire. It actuates thelever I6 (Fig. 1) on which is mounted a gripper H which opens when the lever [B swings to the left so as to slide freely over the wire but in the movement to the right it grips the wire and carries it along with it so that a definite length is introduced into the machine. The length of wire can be altered in known manner by adjusting the effective feed movement. The wire is introduced into the slot 25 in the bending block l2 (Fig. 2). In the example shown, the wire is introduced in the plane in which the cramp is driven and the stroke of the crank 6 is so large that there is suflicient time for the introduction of the wire. The cam Ill serves to sever the length of wire which has been advanced. It operates on a roller I8 which is carried on a member l9 which on the righthand side carries the blade 20. A corresponding blade is carried on the housing 2| (Fig. 1).

Due to the downward movement of the roller l8, the wire is cut by means of these co-operating blades 20, 2|. A spring 22 draws the member l9 upwardly again. In order to allow the cramp to be forced through the work slowly and effectively during that part of the plunger movement in which this operation is timed to occur. the corresponding point 23. of the crank strap 8' where the crank 6 engages it is shaped in the form of a cam (Fig. so as to give a retardation groove, it is clear that the resultant driving stroke will be. a simple harmonic motion. The guide groove, however, is a cam groove which,

broadly speaking, can be described as concave downwardly. The result is that in the first part of its movement from the top dead center position, the crank 6 will impart amore rapid driving movement than if the guide groove were a simple straight groove at right-angles to the driving direction. The more rapid movement 'will persist for about rotation from top dead center. During the succeeding 90 rotation to bottom dead center, the downward concavity of the guide groove serves to reduce the drivin movement, and if the radius of the concavity were equal to the crank radius, the driving movement would be reduced to zero. By suitablevided wherebyat the moment-the wire cramp encounters the work and during the period of its penetration a special pressure is exerted on the plunger l5 carrying'the driver, thereby relieving the load on the crank 6 and its strap 6- or else making them entirely imnecessary. This could be effected, for example, by straightening a toggle by means of a separate drive, a differential gearing or the like. 7,

The bending of the wire to form the cramp and the guidance of its shanks are effected in the following way:

' Firmly mounted on the frame so as to be rotatable about-24 is the bending block II, which by means of the spring 25 is constantly urged inwardly on the.,stitching head (i. e. to the left in' Fig. 2); so that when the wire is introduced it enters the slot 25; On'the other side the cramp support 28 is mounted at 21 on the member 1 JWhIchmoves up and down. The cramp support 2! carries a roller 29 which encounters a cam 30 'which is so shaped that during the downward movement of the bending members I I the cramp support 28 cannot swing forwardly under the action of the spring 3|. Thus the bending membersjll engage the length of wire which is beneaththemand bend it downwardly on the right and the left of the bending block- I! so as to bend choice of theltwo radii, anydesired-slow driving, movement can be produced during phase a rigid block :2 is provided. As the shanks r cramp pass throughthework'they' are progressively bent ,over against H the underside 'of' the work. With this arrangement it is iiidvan'tageous v to subject the points of stitching to a-subsequent pressing operation in a press in order to make the back of the cramp flush with the surface. I v

The adjustment to the thickness of the-work which is to be stitched-is eiiected by means of 'a handwheel 33 (Fig- 13) on-the shaft 34, on which is mounted a worm 35 Which'engages in the worm wheel 36. This rotates the eccentric pin 31 which moves the plunger 38 on whichthe table 39 is carried. The table 39 is locked in the adjusted PQ ition by means of the locking handle.

the work can conveniently be positioned beneath An example of .the second type of clinching mechanism which constitutes a further feature of the present invention is shown in Figs; 14 to 22' of the accompanying drawings,-in which;

Fig. 14 shows a front view of a wire stitching machine provided with the clinching mecha- 30nism between the shanks or; the. cramp so that when subsequently the driver engages the backer the v cramp and thereby expels the bending block 12' to the right (Fig. 3) the crampiscompletely enclosed in the channels in the bending members and after encountering the work cannot buckle under the.-pressure which constantly increases up to the moment of penetration; consequently the cramp must pass through'the material. Ex-

periments have shown thatiron wire of -1 mm.

cross section is capable of penetrating sheet steel of about 2 mm. thickness if the machine and the elements which have to generate} and transmit the eflective pressure are made corre-' spondingly. strong.

which engagethe cramp'shanks after the'cr'amp "has been driven completely through the work, 1

bend them outwardlyand urge them upwardly against the work. mechanism also must be so..stro ng that'ther'e is no yielding so that the wire lies close against the work. when the played and the parts are not further-described. I

Figures 16 to 22 are detail views, in which Figure 16 shows n-shaped cramp an engaging the Figure 17 is a section along XVII of Fig. 16,

Figure18 shows the cramp after thework has been penetrated,

Figure l9=is a section along the offis. 18, v a a Figure 20 shows the ends of the cramp bent over, i

. Figure 21 of 2o,

isa sectionalong the line Figure 22' shows the finished work.

In'so far as parts are shown in Figs. 14 to122.

corresponding to those already described in Figs. 1 to 13, the same reference numerals are em- The wire feeding. and cramp forming and driving mechanisms arethe same as those previously described except that the appropriate length'of wire 4 is fed in by rollers H instead of by the ,oscillatinggripperll. The adjustmentfor differshanks of the cramp are bent outwardly the material beneath the backfofthe cramp can be,

' forced into the cavity-between the two bent ends of-the wire by exercising a correspondingly heavy pressure from above, so-that atthe point ent thicknessesof work who stitched is also the same as that already described. 3 w The clinching mechanism of Figures 14 tow-21 operates on a different principle from that pre-' 'viously described with reference to Figures 11 to 13 and .will-now bedescribed. During the time theshanks of the cramp are being driven through the work by the action of the *stitcher head, the .work is supported from below by a counter -member'ilfl which is in the form of amatrix providedwith slots I l to receive the shanks without deflection, These slots are of substantially the same width asthe shanks'of the cramp and are so arrangedthat they embrace the shanks closely on three sides. On the fourth side, correspondto the length of the slot, room is left for the subsequent bending over or clinching'of the 1 The slots Ill .terminate at sharp'edges of stitching the upper side flush with the surface of the work.

An example of the first-mentioned type of clinching mechanismisindicated in Fig. 1 where 'inthe. surface of the'member llll' sov that on three sides the work islsupported asclose as possible to the point of penetration of the shanks so that a more or less complete punchingaction the.

the liheXV II-j M line tions so as to impart to the staple-entering side is obtained which prevents a breaking away or distortion of the work at the points at which the cramp shanks passthrough it. The length of the slots III should also be as small as possible" so that the bending of the work where it is subjected to the punching pressure is reduced to a minimum. Plungers H2, H3 are moved up and down in these two narrow slots -I I I. The plungers each terminate in a dished depression in which during the upward movement of the plungers the shanks of the cramp are rolled inwardly or outwardly and-finally are urged firmly against the work.

The plungers H2, H3 are secured on a rod Ill which at its lower end is connected to one arm of a bell crank lever I22, to'the other arm of which an internally threaded sleeve I24 is detachably secured by a pivot 'pin I2I. The sleeve I24 is threadedly engaged with a rod I23 which is moved to and fro by meansof a cam mounted on a driven shaft of the machine. In this .way the clinching plungers H2, 3 are actuated at the appropriate moment. By releasing the pin vI2I, the sleeve I24 can be rotated relatively to the rod I23 for adjustment purposes.

In the foregoing and in the accompanying drawings the invention has been set forth with reference to an arrangement for automatic cramp formation from wire fed to the machine,

but it will be apparent that a machine according to the invention could be adapted to operate with pre-formed cramps which are introduced into a magazine provided on the machine.

I claim:

1. A machine for uniting overlapping layers b driving n-shaped 'wire cramps therethrough and clinching the shanks of the cramps on the other side of the work, comprising a work support, said support having two slots therein, one for each shank of the cramp, of substantially the same width as the cramp shanks to permit the unobstructed emergence of said shanks while supporting the work as close as possible to the points of emergence of the shanks, said slots extending in the direction of the back of the cramp and outwardly from the points of penetration of the shanks, dished plungers movable in said slots to clinch the shanks outwardly, and positive cam-operated means for moving said plungers'to perform said clinching operation after the cramp has been driven through the work to its full extent. v

2. A machine for uniting by means of wire of the work a convex curvature opposite to that which the cramp driving operation tends to impart to the work.

3. A wire-stapling machine comprising a support for sheet metal material to be stapled, a staple-receiving guide having walls engaging the outer three sides of each shank of the staple,

" a wedge-shaped member having its parallel sides in engagement with theinner sides of the shanks of the staple and cooperating with the walls of the guide to completely'enclose all sides of the shanks of the staple, said wedge-shaped member having-its inclinedsides lying between the bridge of the staple and the material to be stapled,. means for pressing the lower ends of the guide against the material to be stapled and the shanks cramps overlapping plates of small thickness but 4 considerableresistance to the penetration of the cramps, comprising plate supporting means on of the staple through the material to be stapled, means operable in synchronism with the pressing means for -retracting the wedge-shaped member from the staple as it is pressed into the material, said support having two slots formed therein of a width substantially equal to the thickness of the staple shanks, of a length substantially equal to the length of the shank ends projected through the material to be stapled, and

spaced apart a distance substantially equal to the distance between the shanks of the staple whereby the shanks will be engaged by three walls of said slots, and means reciprocably mounted in said slots for bending the ends of the shanks extending down into the slots outwardly and back against the material to be stapled.

4. A wire-stapling machine comprising a support for material to be stapled, a staple-receiving guide having walls engaging the outer three sides of each shank of the staple, a wedge-shaped member having its parallel sides in engagement with the inner sides of the shanks of the staple andcooperating with the walls of the guide to completely enclose all sides of the shanks of the staple, said wedge-shaped member having its inclined sides lying between the bridge of the staple and the material to be stapled, means for pressing the lower ends of the guide against the material to be stapled and the shanks of the'staple through the material to be stapled, and means/ operable in synchronism with the pressing means for retracting the wedge-shaped member from the staple as it is pressed into the material,'said support having two slots formed therein of -a width substantially equal to the thickness of the staple shanks,- of a length substantially equal.

"to the length of the 'shank ends projected tance between the shanks of the staple whereby the shanks will be engaged by three walls of said slots, the upper surface of the support being convex and the lower ends of the staple guide being spaced apart to impart a convex configuration to the upper staple-entering surface of the material to be stapled. 4

OSKAR KLEINSCHMIT. 

